Oxidation inhibitor for insecticides



Patented Jan. 17, 1939 OXIDATION mmnrron roa INSECTICIDES Dalton B.Falcon, Beacon, N. Y., assignor to Hammond Paint & Chemical 00., Inc.,Beacon, N. Y., a corporation of New York No Drawing. Application October24, 1933,

Serial No. 695,001

5 Claims.

This invention relates, generally, to insecticides and the invention hasreference, more particularly, to means for preventing the more or lessrapid deterioration of insecticides such as pyrethrum and rotenone inuse.

Organic insecticides heretofore produced such as pyrethrum and rotenonehave been found to lose their toxic properties more or less rapidly sothat ofttimes after these substances have been stored or unused for atime their value as insecticides is greatly reduced and cannot producethe results desired.

This is particularly true of insecticide solutions, and it has beenknown that the presence of alkaline materials, such as sodium andpotassium salts in the insecticide solution or the presence of moisturealso greatly accelerates the rate of deterioration. Also, exposure tothe air and sunlight serve torapidly lower the toxic value of suchsolutions. v

The deterioration also proceeds even though the insecticide solutionsare confined and isolated from light, due, I have found, to thecatalytic action of small amountsof inorganic substances present and tothe natural affinity of such organicsubstances as pyrethrum and rotenonefor oxygen. This deterioration also takes place in powdered organicinsecticides but at a slower rate than when the insecticides are insolution.

In my work, I have determined that oxidation is the main cause of lossof toxicity in insecticides and that the rate of deterioration varies inproportion to the ability of oxygen to come in contact with theindividual units of the toxic substances.

The principal object of the present invention is to provide a method forpreventing the rapid oxidation and consequent deterioration of organicinsecticides.

Another object of this invention is to provide means which when added toorganic insecticides will enable such insecticides to be stored forrelatively long periods without appreciable loss of toxicity.

Still another object of this invention is to provide means which may bereadily dispersed throughout the mass of an insecticide, the said meansserving to blanket and protect the toxic ingredients of the insecticideagainst oxidation, thereby enabling such protected insecticide to beleft exposed to light and air without appreciable deterioration of thetoxic character of the same.

These objects are achieved by the following invention, that enablesorganic insecticides which possess the objections here underconsideration,

to be stabilized and protected from deterioration without altering theirtoxic properties or field of use, by additions of oxidation inhibitorsand by controlling the character and magnitude of such additions so thatthe desired protection of the insecticide composition is obtained forunlimited periods.

In particular, it has been found that relatively small amounts ofphenolic or amino compounds, including dihydric and polyhydric phenols,their esters, and naphthols and their esters are especially adaptablefor use as oxidation inhibitors for these purposes;

In carrying out the present invention, extract derivatives from toxicorganic substances are prepared according to the known methods of theart using various solvents and adding the oxidation inhibitors ornegative catalysts of this invention. It was found that various solventsrequired greatly varying percentages of negative catalysts for producinguniform results. Also,

the relative solubility of a particular oxidation inhibitor in anyparticular solvent was found to be highly important in determining thepercentage of inhibitor to be used. To be efiective, it is essentialthat the oxidation inhibitor be completely dispersed throughout theinsecticide composition and that no separation occurs during storageafter manufacture.

Some solvents permit the use of certain .types of inhibitors which arenot readily dispersed in other types of solvents. I have found that themore completely the oxidation inhibitor is dispersed in the vehicle themore effective the inhibitor becomes.

The following products are specific examples of some of the phenolic,amino, dihydric and polyhydric phenols and their esters and naphtholsand their esters which have been found satisfactory as oxidationinhibitors or negative catalysts in the present process: Beta naphthol,resorcinol, alpha naphthol,

hydroquinone, eugenol,

pyrogallol, thymol, p-amino phenol, guaiacol,

lignicol, benzidine,

hexamethylene tetramine,

part in determining the quantity or proportion of oxidation inhibitornecessary to protect the insecticide against deterioration.

The various solvents that may be used as a vehicle such as alcohol,acetone, carbon tetrachloride, ethylene dichloride, neutral petroleumoil, kerosene, gasolene, mineral spirits, etc., or mixtures of two ormore of these solvents vary in their respective abilities to dispersethe inhibitor or negative catalyst used in any instance so thatdifferent proportions of any particular catalyst are necessary withdifferent vehicles. Acetone, "for example, which may contain somemoisture requires more negative catalyst to inhibit oxidation than 2.ve-

hicle of alcohol. Vehicles containing sulphonated oils or moisturerequire larger proportions of inhibitors than those not having theseingredients therein. I

In general, I have found that the quantity of the negative catalystoroxidation inhibitor necessaryto overcome premature oxidation ordeterioration of the toxic principles of organic insecticides will beless than 1% by weight on the basis of total composition. In some casesquantities of inhibitors as low as .05% or even lower by weight of thetotal composition have appreciable eflects, while in other cases .6% and.8% are more efiective. In rare combinations of vehicles, quantities ofinhibitors in excess of 1% and up to the amount of 1.5% by weight of thetotal combination have been required to obtain the desired results. Itis understood however that I do not wish to limit myself entirely topercentages below 1.5%, because greater percentages of the inhibitorsmay be used, although the additional benefits or protection derived bythe use of larger percentages than 1.5% are generailysubstantiallynegligible. I

Owing to the great number and diversity of insecticide compositionscomprising toxic substances such as rotenone, pyrethrum, derris, etc.,and a great variety of vehicles and vehicle combinations, whichcompositions I have found to be protected against oxidation by thepreviously mentioned inhibitors, it is impracticable to list theingredients of all such compositions. However, a few-representativeexamples of insecticidecompos'itions are given below, the ingredientslisted being mixed together with stirring in the percentages given byweight:

Composition No. l P 2232 33 Pyrcthrum 2. 5

Giminml 005 Almhnl 90. 00 Acetone 7. 495

Percent by Composition N0. 2 weight I Derris. 3. 00 Beta napthol 003Ethylene dichloride. 2 ()0 lcohol 94. 97

Composition No. 3 2322 3 Pyrethrum 1. 2 Rntemme l. 0 Hydroqninnnn I 0025Carbon tetrachloride 1. 0 A lnnhnl 96. 7975 It will be noted thatin-none of the above examples was it necessary for the oxidationinhibitant to exceed .03% by weight of the total composition, therebydemonstrating the practicability of my method of oxidation inhibitionfrom a commercial standpoint. In the first three examples given, thevehicles used consisted of a combination of two solvents, namelyalcohol-acetone, ethylene dichloride-alcohol, and carbontetrachloride-alcohol, respectively, while in the last two exampleskerosene and alcohol were used singly as vehicles, thereby illustratingthe great variety of vehicles possible. In some instances other carryingagents such as water or water and soap are used with the vehicle.

After careful and long experimentation I have found that the very bestoxidation inhibitor under all conditions is hydroquinone, although thisis not the easiest of the inhibitors to incorporate into the insecticidemixtures. The second best inhibitor and really the most practicalbecause of the ease with which the same may be thoroughly dispersedthroughout various vehicles by merely mixing'the same in the vehicles,is guaiacol and its counterpart known as lignicol. Next in the line ofdesirability and effectiveness come alpha napthol and beta. napthol,although they offer the same handicaps of incorporation as found in theuse of hydroquinone. I have found that the rest of the list ofinhibitors previously given stand about on an even basis ofefiectiveness. It is not necessary to use one inhibitor alone for I havefound that intermixing two or more inhibitors such as guaiacol andhydroquinone together and adding to the insecticide solvent mixtureproduces results comparable with either one of these inhibitors usedsingly. Thus the inhibitors as well as thesolvents offer an opportunityof blending which means a myriad of formulations, most of which are oflittle interthe stabilizing compound issubstantially within the range of.0025 to 1.5 by weight of the total insecticide.

DALTON B. FALCON.

